1. Field of the Art
The present invention relates to a dental attachment that can be used to fix a denture to a dental implant keeper by the use of a magnetic force.
2. Prior Art
Various dental attachments using magnetic attractive force have been proposed in dental treatments, because it is a simple method to take off and fix the denture.
For example, the dental attachment 9 shown in Japanese Laid-Open Patent Number 9-224959, as shown FIG. 6, consists of an implant 91 acting as an abutment embedded in the jawbone, a keeper 93 fixed to this implant, and a magnetic assembly 95 which has an attractive surface 950 that attracts the attracted surface 930 of the keeper 93 by a magnetic attractive force.
The keeper 93 is fixed to said implant 91 by screwing screw part 931 of keeper 93 into screw hole 911 of implant 91. With this, the contact faces 912 and 932 fit together precisely and prevent alien substances from entering between implant 91 and keeper 93.
However maintenance of a fixing force solely by screwing the screw part 921 to screw hole 911 is not enough, and looseness may be caused during use of said dental attachment. This looseness may cause a sudden deterioration of fixation and cleanliness.
Therefore the development of a dental attachment that can maintain said fixation and stability between a keeper and an implant by the way of a screw is desired.
Taking into consideration the abovementioned requirements, the present invention provides a dental attachment that can improve the fixation and stability between an implant and a keeper.
The present invention is directed to a dental attachment which comprises an implant embedded in a jawbone, a keeper supported by said implant, and a magnetic assembly that has a attractive face that attracts an attracted face of said keeper by a magnetic attractive force.
The keeper has a main body that has said attracted face, a screw part that is located at the center of a back face which is opposite to said attracted face of said main body, a conically tapered shaft at the base end of said screw part, and a projecting ring part that projects toward the shaft to form a ring-shaped groove with said tapered shaft along the circumference of said back face.
Said projecting ring part has a slanted inner face that tapers toward a pointed end, and an acute angle pointed end that actually looks like an acute angled shape that intersects the outer face.
Said implant has a screw hole part into which said screw part of said keeper can be screwed, a conical tapered hole part which extends upward from the open side of said screw hole part and has approximately the same incline angle of said tapered shaft, and an inclining end face which slants upwards to the circumference of the opening of the tip of the implant.
The dental attachment has the feature such that when said keeper and said implant are screwed together, there is close contact of said screw part to said screw hole part, said tapered shaft to said tapered hole part, said inner face of said acute angle pointed end of said projecting ring part and said inclining end face of said implant, and at least said acute angled pointed end of said projecting ring part is elastically transformed in a radial direction.
The presently invented dental attachment has, as explained above, said tapered shaft of said keeper and an acute angled pointed end of said projecting ring part, while said implant has said tapered hole and said inclining end face. When a keeper is connected to an implant, as explained above, said tapered shaft is closely fitted to said tapered hole, and at the same time, said inner face of said acute angled pointing end and said inclined end face come into contact, and at least said acute angled pointed end of said projecting ring part is elastic transformed in a radial direction.
In this manner way, the connecting force between said keeper and implant is maintained by both the frictional force between said tapered shaft and tapered hole and the frictional force between said acute angled pointed end and said inclined end face. In particular, the frictional force between said tapered shaft and tapered hole part gives a much greater connecting force preventing loosening of the screw.
By the contact of said acute angled pointed end of said projecting ring part and said inclining end face, a precise fit can be made.
Even excellent parts processing in the prior art has had difficulty to achieve the accuracy of dimensions to adequately screw said tapered shaft to said tapered hole part and at the same time make said acute angled pointed end of said projecting ring part touch said inclining end face. But if said acute angled pointed end can be elastic transformed to some degree during screwing, adequate processing accuracy of a keeper and implant can be achieved, and in addition the two abovementioned places can be firmly fit together.
When connection is made in the abovementioned fashion where said acute angled end part is elastically transformed, said tapered shaft can be screwed into said tapered hole part and at the same time said acute angled pointed end of said projecting ring part can be connected to said inclining face without difficulty of said processing art. Thus both excellent prevention of screw loosening and prevention of filth intrusion can be achieved.
Therefore, according to the present invention, a dental attachment with an improved connection force and firm fitting between an implant and keeper can be achieved.